O o o o o o o o



'A. c. E. HOJGAARD.

- ELECTRIC CONTACT DEVICE.

APPLICATION FILED` MAR. 22.1919

'1,3 1 5,306. Patented sept. 9,1919.

@MaM/@ J '4/ /Vrja ANDERS CHRISTIAN EMIL-HOJGAAD, COPENHAGEN, DENMARK.

ELECTRIC CONTACT DEVICE.

Specification of Letters Patent.

Patented Sept. 9, 1919.

Application filed March 22, 1919. Serial No. 284,465.

To all '1o/wm t may concern:

Be it known that I, ANDERS CHRISTIAN EMIL HCJCAARD, a subject of the King of Denmark, residing at Copenhagen, in the Kingdom of Denmark, have invented new and useful Improvements in Electric Contact Devices, of which the following is a specification.

The present invention relates to an elec-` tric contact apparatus. The apparatus is fitted with a set of pointers, sliding contacts or the like, each of which are to be adjusted in a quite definite manner depend ing on any previous adjustment of the apparatus, in order that the desired Closing of the circuit may be attained.

One manner of constructing the invention is shown, by way of example, on the drawing, where j Figure 1 shows the apparatus in front elevation,

Fig. 2 the same in rear elevation, and

Fig. 3 another form `of construction of the apparatus in front elevation.

ln practice, the rear side of the apparatus must be inaccessible from the front `side. The apparatus may, for instance, be placed on a door, so that the front side is accessi ble only from the outside, the rear side only from the inside.

On the rear side, there are provided a number of Contact-heads (on the drawing 1 to `18) disposed 'in a circle and insulated from each other. At the center of this circle there are provided two arms a, b forming sliding contacts whose pivots c, d encircle one another, without being insulated from one another, and may be rotated independently of one another. The arms a and Z) are revolved from the face of the apparatus by turning the pointers 'u and w provided there and being firmly connected each to one of the pivots c and (Z for the rear-side arms L and b, respectively. The pointers on the front side are opposite the arms on the rear-side and point on a numbered dial j t, whose numbers are the same as the numbers of the contact-pieces and are placed at the same radii as these. On the rear side and outside of the row of contact-heads, there is also provided a circular ring f of metal and, sliding on this ring but insulated therefrom, there are provided two metal handles g, h, whereto the outer conductors zu and y of the apparatus are fastened. Each of the handles g and It is fitted with a resilient sliding contact fm and n, respectively, traveling on top of the contact-heads, when the handles are moved along the metal ring j'. If now the handles `are adjusted for instance on the contacts S and 37, it is obvious that the conductive con nection` through the apparatus from the conductor w to the conductor y can only be effected when the arms a, b are caused to touch the same contacts, which is when the pointers o and w on the front side point on the numbers S and 37, while any other adjustment of the pointers and, thereby, of the arms a and Z; will bein vain. The handles g and h' may be adjusted into 1128 different positions, and` for each of these there may be performed 1127 resultless adjustments of the pointers.

From this it will appear `that even for an apparatus with a8 contacts it is exceedingly diiiicult to find the correct position of the pointers by experiment. The more contactheads there are provided, the more diflicult will the adjustn'lent be to the uninitiated, but the difficulty in that respect is increased to a far greater extent, if two or more such apparatuses be combined in series, or if the apparatus has two or more sets of pointers or arms, and two or more corresponding sets of handles connected in series. Two apparatuses with 48 contact-heads, for instance, have more than 121# million of different pointer-positions, out of which only one in each single case is the correct one.

Instead of being circular, as in the construction shown in Figs. 1 and 2 by way of example, so that the closing of Contact is effected by rotation of pointers, the apparatus may be rectangular, as shown in Fig. 3, and the contact-heads may be disposed in two rows along which the terminals g, h of the conductors may slide, while pointershaped slides ful, w1 may be moved, in corresponding manner, on the front side of the apparatus along scales provided there and corresponding to the contact-heads. These last mentioned corresponding slides must, in that case, be connected electrically to each other.

The electric contact apparatus here described may be used to advantage in connection with electrical locks, as only the person having adjusted the terminals of the conductors, or the person having received information about the adjustment of these terminals, will be able to effect closure of the circuit required for opening the lock. Burglaries by means of counterfeit keys or skeleton keys will thus be precluded'.

It is obvious that the use of the apparatus in connection with electrical apparatus, machines, vehicles or ships precludes any illicit use of the latter.

Having now particularly described and ascertained the nature of my said invention and in what manner the same is to be performed, I declare that what I claim is 1. In an electrical contact device, an insulating plate, contacts disposed on one side of said plate and alterable in position thereon, relatively movable members for closing a circuit through said contacts disposed on the same side'of said plate, and means operable from the other side thereof for actuating said members. Y f

2. Electric contact device containing a system of accessible adjusting members and of inaccessible contact-members, the said adjusting members being paired with and arranged to actuate said contact members, and each pair beingV adapted to be adjusted independently ofthe other pair, a series of fixed contact-heads, and adjustable terminals for the conductors of the circuit, the said contact-heads being disposed within reach of the said contact-members and terminals, and being arranged to effect electrical connection between the said contactmembers and the said terminals, on adjustment of the said contact-members in a predetermined manner known only to the initiated. and dependent upon the position in which the said terminals have been set.

3. Electric contact device containing a system of accessible adjusting members and of inaccessible contact-members, each of the said adjusting members being paired with and arranged to actuate a contact member and each pair being adapted to be adjusted independently of the other pair, a series of inaccessible fixed contact-heads disposed in a circle, and terminals for the conductors of the circuit, the said terminals being disposed slidably on a ring concentric with the circle of contact-heads, the said contact-heads being disposed within reach of the said contact-members and terminals, and being arranged to effect electrical connection between the said contact-members and the said terminals, on adjustment of the said contact-members in positions dependent upon the setting of said terminals and known only to the initiated.

In testimony whereof I have signed my name-to this specification.

ANDERS CHRISTIAN EMIL HOJGAAltl).

Witnesses V. BELSCHNER, NAGELHARD AHRADREW.

Copies of this patent may be obtained for five cents each, by addressing the Commissioner of Patents, Washington, D. 0. 

